Cystitis is a general term for any inflammation of the urinary bladder. It may be caused by an infection or irritation, both of which may be the result of a wide variety of inciting issues.
Cystitis is common in both dogs and cats, though their causes differ significantly depending on the species. The signs of disease, typically frequent, strained, and painful urination, are almost identical in both. Blood in the urine, though common, may not be present -- or at least not visible to the unaided eye.
The causes of cystitis are many and vary significantly between dogs and cats as well as males and females.
In both species:
Diabetes mellitus (sugar in the urine feeds nearby bacteria, thereby aiding their proliferation, which leads to cystitis)
Skin diseases, diarrhea, vaginitis, prepucial infections (or anything else that leads bacteria to proliferate abnormally near the opening of the urethra, as bacteria will often ascend this structure and thereby colonize the bladder)
Bladder stones (these can lead to irritation and subsequent infection, but take note that stones can also be caused by chronic cystitis, too)
Cancer of the bladder (or of adjacent structures)
Neurologic diseases (particularly should these lead to prolonged urine retention)
Medications or diseases that may affect the body's normal immune function adversely (thereby predisposing the bladder to infections)
Complications arising from feline idiopathic cystitis, also known as feline lower urinary tract disease (an inflammatory condition for which bacterial infection is currently considered an unlikely component)
Bladder stones (though less commonly than in the dog)
Note: Cystitis is widely perceived by pet owners as an infectious condition of bacterial origin. However, this is not the case in over 95% of cats.
Cushing's disease (this condition decreases the body's immune response and is often related to infections that arise from the skin, as Cushing's disease commonly leads to skin conditions that may result in infections)
Hypothyroidism (this can predispose dogs to skin diseases that may lead to skin infections and subsequent bacterial colonization of the bladder)
For female dogs:
Allergic skin disease (in females, skin infections surrounding the vulva are common in patients with allergic skin disease)
Recessed or "hypoplastic" vulva (urine tends to collect on the skin in dogs with this conformational problem, which is typically either inherited or exacerbated by excess weight)
Hormone-related incontinence (this common condition affects spayed female dogs and is characterized by an incompetent bladder sphincter and "leaking" urine, thereby allowing for ascending infections)
Ectopic ureter (this congenital, inherited condition allows female dogs to urinate or "leak" abnormally, too)
As should be evident from the list above, female dogs are more likely to suffer cystitis than males.
Symptoms and Identification
Dogs and cats with cystitis may show one or more of the following signs:
Dogs and cats with cystitis will typically urinate small volumes frequently. Smelly, cloudy, or bloody urine may be appreciated. Straining to urinate (squatting or heading to the litterbox frequently) is considered good evidence of the pain or irritation typical of infected, irritated, or otherwise inflamed bladders.
Definitive diagnosis of cystitis is often achieved via urinalysis and "culture and sensitivity." The former is a test that evaluates the urine chemically along with its cells and other components by microscopy. The latter is a test that determines the kind of bacteria growing in the urine as well as the antibiotics it's susceptible to.
Additional testing is considered very important to determine the cause of the cystitis, if it's not already evident, and to investigate its underlying causes, too:
Complete blood count
Serum biochemistry analysis
Abdominal X-rays (with or without contrast)
Testing for immunosuppressive conditions
Allergy testing (in dogs)
Thyroid hormone testing (in dogs)
Cushing's disease testing (in dogs)
Biopsy of bladder
No breed predisposition has been noted for cystitis in either dogs or cats. However, some of the underlying causes of urinary tract infections may be influenced by genetic factors predisposing pets to these infections.
Breeds of dogs and cats genetically predisposed to any of the above mentioned inciting or underlying conditions will be overrepresented.
Treatment of cystitis requires targeted antimicrobial therapy (antibiotics) if bacterial infection is a factor and/or anti-inflammatory treatment, along with treatment of any underlying condition.
Diet changes are often part of the long-term management of these conditions. Surgical options may be deemed necessary for those suffering conformational defects or conditions otherwise amenable to surgical solutions (some cancers, for example).
Identifying and treating these underlying conditions is fundamental to the long-term success of cystitis treatment.
The cost of diagnosis and treatment of cystitis is often considered quite manageable by most pet owners. Treatment of the underlying conditions, however, may prove less affordable -- particularly should surgical solutions play a leading role.
Limiting the breeding of dogs and cats affected by heritable conditions that predispose them to cystitis is the ideal means of prevention.
In pets already affected by these inciting conditions, preventing cystitis is accomplished by identifying and treating them early -- if possible -- before it ensues.
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